CVE-2024-27399

Bluetooth: l2cap: fix null-ptr-deref in l2cap_chan_timeout

MEDIUM

5.5

CVSS Score

Published: May 13, 2024 at 10:24 AM UTC

Updated: June 17, 2026 at 07:19 AM UTC

3 products affected across 3 vendorsLinux KernelDebian LinuxFedora

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Severity

MEDIUM5.5

Exploit prediction

EPSS 0.3%

SSVC

No known exploit

Description

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: l2cap: fix null-ptr-deref in l2cap_chan_timeout There is a race condition between l2cap_chan_timeout() and l2cap_chan_del(). When we use l2cap_chan_del() to delete the channel, the chan->conn will be set to null. But the conn could be dereferenced again in the mutex_lock() of l2cap_chan_timeout(). As a result the null pointer dereference bug will happen. The KASAN report triggered by POC is shown below: [ 472.074580] ================================================================== [ 472.075284] BUG: KASAN: null-ptr-deref in mutex_lock+0x68/0xc0 [ 472.075308] Write of size 8 at addr 0000000000000158 by task kworker/0:0/7 [ 472.075308] [ 472.075308] CPU: 0 PID: 7 Comm: kworker/0:0 Not tainted 6.9.0-rc5-00356-g78c0094a146b #36 [ 472.075308] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu4 [ 472.075308] Workqueue: events l2cap_chan_timeout [ 472.075308] Call Trace: [ 472.075308] <TASK> [ 472.075308] dump_stack_lvl+0x137/0x1a0 [ 472.075308] print_report+0x101/0x250 [ 472.075308] ? __virt_addr_valid+0x77/0x160 [ 472.075308] ? mutex_lock+0x68/0xc0 [ 472.075308] kasan_report+0x139/0x170 [ 472.075308] ? mutex_lock+0x68/0xc0 [ 472.075308] kasan_check_range+0x2c3/0x2e0 [ 472.075308] mutex_lock+0x68/0xc0 [ 472.075308] l2cap_chan_timeout+0x181/0x300 [ 472.075308] process_one_work+0x5d2/0xe00 [ 472.075308] worker_thread+0xe1d/0x1660 [ 472.075308] ? pr_cont_work+0x5e0/0x5e0 [ 472.075308] kthread+0x2b7/0x350 [ 472.075308] ? pr_cont_work+0x5e0/0x5e0 [ 472.075308] ? kthread_blkcg+0xd0/0xd0 [ 472.075308] ret_from_fork+0x4d/0x80 [ 472.075308] ? kthread_blkcg+0xd0/0xd0 [ 472.075308] ret_from_fork_asm+0x11/0x20 [ 472.075308] </TASK> [ 472.075308] ================================================================== [ 472.094860] Disabling lock debugging due to kernel taint [ 472.096136] BUG: kernel NULL pointer dereference, address: 0000000000000158 [ 472.096136] #PF: supervisor write access in kernel mode [ 472.096136] #PF: error_code(0x0002) - not-present page [ 472.096136] PGD 0 P4D 0 [ 472.096136] Oops: 0002 [#1] PREEMPT SMP KASAN NOPTI [ 472.096136] CPU: 0 PID: 7 Comm: kworker/0:0 Tainted: G B 6.9.0-rc5-00356-g78c0094a146b #36 [ 472.096136] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu4 [ 472.096136] Workqueue: events l2cap_chan_timeout [ 472.096136] RIP: 0010:mutex_lock+0x88/0xc0 [ 472.096136] Code: be 08 00 00 00 e8 f8 23 1f fd 4c 89 f7 be 08 00 00 00 e8 eb 23 1f fd 42 80 3c 23 00 74 08 48 88 [ 472.096136] RSP: 0018:ffff88800744fc78 EFLAGS: 00000246 [ 472.096136] RAX: 0000000000000000 RBX: 1ffff11000e89f8f RCX: ffffffff8457c865 [ 472.096136] RDX: 0000000000000001 RSI: 0000000000000008 RDI: ffff88800744fc78 [ 472.096136] RBP: 0000000000000158 R08: ffff88800744fc7f R09: 1ffff11000e89f8f [ 472.096136] R10: dffffc0000000000 R11: ffffed1000e89f90 R12: dffffc0000000000 [ 472.096136] R13: 0000000000000158 R14: ffff88800744fc78 R15: ffff888007405a00 [ 472.096136] FS: 0000000000000000(0000) GS:ffff88806d200000(0000) knlGS:0000000000000000 [ 472.096136] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 472.096136] CR2: 0000000000000158 CR3: 000000000da32000 CR4: 00000000000006f0 [ 472.096136] Call Trace: [ 472.096136] <TASK> [ 472.096136] ? __die_body+0x8d/0xe0 [ 472.096136] ? page_fault_oops+0x6b8/0x9a0 [ 472.096136] ? kernelmode_fixup_or_oops+0x20c/0x2a0 [ 472.096136] ? do_user_addr_fault+0x1027/0x1340 [ 472.096136] ? _printk+0x7a/0xa0 [ 472.096136] ? mutex_lock+0x68/0xc0 [ 472.096136] ? add_taint+0x42/0xd0 [ 472.096136] ? exc_page_fault+0x6a/0x1b0 [ 472.096136] ? asm_exc_page_fault+0x26/0x30 [ 472.096136] ? mutex_lock+0x75/0xc0 [ 472.096136] ? mutex_lock+0x88/0xc0 [ 472.096136] ? mutex_lock+0x75/0xc0 [ 472.096136] l2cap_chan_timeo ---truncated---

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Debian Linux · Debiandrupal

95%

10.0

Fedora · Fedora Projectrpm

95%

39 40

Linux Kernel · Linux

95%

3.4 ≤ v < 4.19.3143.4 ≤ v < 5.10.2173.4 ≤ v < 5.15.1593.4 ≤ v < 5.4.2763.4 ≤ v < 6.1.913.4 ≤ v < 6.6.313.4 ≤ v < 6.8.103.4 ≤ v < 6.94.20 ≤ v < 5.4.2765.11 ≤ v < 5.15.1595.16 ≤ v < 6.1.915.5 ≤ v < 5.10.2176.2 ≤ v < 6.6.316.7 ≤ v < 6.8.103.43df91ea20e744344100b10ae69a17211fcf5b2076.9 rc1 6.9 rc2 6.9 rc3 6.9 rc4 6.9 rc5 6.9 rc6 6.9 rc7

Vendor states this is fixed in 6466ee65e5b27161c846c73ef407f49dfa1bd1d9 (fixed)

Vendor states this is fixed in 6acb75e7ed600d0bbf7bff5628aa8f24a97978c (fixed)

Vendor states this is fixed in 8960ff650aec70485b40771cd8e6e8c4cb467d33 (fixed)

Vendor states this is fixed in 955b5b6c54d95b5e7444dfc81c95c8e013f27ac0 (fixed)

Vendor states this is fixed in adf0398cee86643b8eacde95f17d073d022f782c (fixed)

Vendor states this is fixed in e137e2ba96e51902dc2878131823a96bf8e638ae (fixed)

Vendor states this is fixed in e97e16433eb4533083b096a3824b93a5ca3aee79 (fixed)

Vendor states this is fixed in eb86f955488c39526534211f2610e48a5cf8ead4 (fixed)

Vendor states this is fixed in 3.4 (unaffected)

Vendor states this is fixed in 4.19.314 (unaffected)

Vendor states this is fixed in 5.10.217 (unaffected)

Vendor states this is fixed in 5.15.159 (unaffected)